Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
  • B24C7/00—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts
  • B24C7/0092—Equipment for feeding abrasive material; Controlling the flowability, constitution, or other physical characteristics of abrasive blasts the abrasive material being fed by mechanical means, e.g. by screw conveyors
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
  • B24C1/00—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods
  • B24C1/003—Methods for use of abrasive blasting for producing particular effects; Use of auxiliary equipment in connection with such methods using material which dissolves or changes phase after the treatment, e.g. ice, CO2
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25C—PRODUCING, WORKING OR HANDLING ICE
  • F25C1/00—Producing ice

Definitions

• the present invention relates to the surface treatment by impacts of solid particles projected under pressure onto a support to be treated. It relates in particular to a surface treatment using ice balls and the manufacture of these ice balls.
• a first method consists in projecting a jet of sand under strong pressure on the object to be treated.
• Other similar materials can be used such as: corundum, iron shot, polyethylene balls, or crushed peach kernel.
• a second method consists in projecting a jet of dry ice particles, that is to say of a carbon dioxide hybrid, called dry ice.
• a jet of dry ice particles that is to say of a carbon dioxide hybrid, called dry ice.
• two large masses are divided into fine particles by grinding, then sprayed under pressure on the part to be treated.
• a third method consists in projecting a multiphasic jet, that is to say liquid-solid, in which frozen particles are entrained in a stream of cold liquid and projected onto the object to be cleaned.
• a multiphasic jet that is to say liquid-solid, in which frozen particles are entrained in a stream of cold liquid and projected onto the object to be cleaned.
• the ice is obtained by grinding ice cubes and the liquid is water under pressure.
• the object of the present invention is therefore to provide a device for manufacturing and projecting ice balls, for cleaning or decontamination purposes, and this in a single technological system, where all of the operations are carried out in continuity.
• the first object of the invention is a method of manufacturing ice balls. It consists in dispersing droplets of water in a column of cold gas. The water droplets pass by gravity through this column of cold gas and cool to solidify superficially, before falling into a bath of coolant, where they solidify entirely in the form of ice balls.
• the cold gas and the coolant consist of the same body in the liquid phase and in the gas phase, namely nitrogen.
• the gas flow is in this case three hundred and fifty times greater than the water flow.
• a second main object of the invention is the implementation of this process by a device which comprises an exchange column supplied with cold gas by an inlet and on an upper end of which is disposed a water injector using a large number of holes, and a receptacle supporting the exchange column and comprising a coolant supply ramp, a cone for receiving the ice balls in its lower part and an orifice for discharging the ice balls at the bottom of the cone .
• the embodiment of the device provides that the walls of the column and of the receptacle are made up of two stainless steel walls, the space between the two walls being filled with polyurethane foam.
• a third main object of the invention is a device for manufacturing and projecting ice balls using the device for manufacturing ice balls described above.
• an extraction screw a first end of which is placed below the orifice of the receptacle to evacuate the ice balls from the receptacle, - a cold gas inlet at a second end of the extraction screw, to push the ice balls in a first flexible conduit,
• a nozzle for projecting the ice balls placed at the end of the first flexible duct, and having a cold gas inlet for projecting ice balls.
• the extraction screw is inclined and has a coolant recovery conduit to return it to the receptacle. It can be of the Archimedes screw type of pure form.
• the two cold gas supplies at the upper end of the extraction screw and at the projection nozzle are supplied by the same distributor. It is also planned in this case to use a storage tank for the coolant connected to an evaporator to supply the pressurized cold gas necessary to supply the distributor, and connected to the coolant supply manifold in the receptacle. The gas cooler is then placed at the outlet of the evaporator.
• FIG. 1 represents a diagram of the devices according to the invention
• FIG. 2 shows an exploded diagram of the type of injector used in the devices according to the invention
• Figure 3 shows a diagram of the devices according to the invention equipped with means for producing the coolant and cold gas.
• the invention makes it possible to manufacture a frozen liquid material in solid form, which can then be transported and projected by a gas onto an object to be treated.
• the principle of the invention consists in obtaining, by a first phase, partially frozen ice balls, by dispersion of a spectrum of water droplets in an exchange column open at its top, by direct contact with a refrigerant gas headed against the tide.
• the second phase of cooling is the final solidification, which takes place in a coolant bath, placed below the exchange column.
• the obtaining of ice balls is carried out by means of the manufacturing device according to the invention, represented on the left of this figure.
• the device is supplied with water by a pipe 1, the flow rate of which is regulated by a flow meter
• This pipe 1 leads to an injector 2, placed at the upper end of the device.
• This injector is provided with a large number of holes 4, through which the spectrum of droplets is formed intended to produce the balls of ice.
• the spectrum of the droplet diameter can be adjusted by the prior choice of the diameter for drilling the holes 4.
• the spectrum of sizes of water drops ranges from 0.5 mm to 2 mm. Diameter and number of injectors are calculated for a flow ranging from 40 to 60 l / hour without significantly altering the size of the beads.
• the water injection system consists of two plates 50 and 52.
• the upper plate 50 cylindrical, with a thickness of about 5 mm in PVC is pierced in its center with a hole in which a tube 54 arrives which serves as a water supply.
• the lower plate 52 is cylindrical, about 5 mm thick in PVC and is pierced with chamfered holes 56 on the inside. The whole of this face undergoes fine sandblasting to ensure capillarity which allows the water to regularly wet the entire surface.
• needles 58 are inserted by force which are the water injectors.
• a nickel foam plate 62 covers the entire face and acts as a capillary network balancing the water pressure on the injectors 58.
• a stainless steel wire cloth 64 covers the entire surface distributing the flow rate ensuring the upper plate 50 over the entire surface of the foam plate nickel 62.
• the reservoir formed for the plates 50 and 52 is closed by a set of eight bolts placed at 45 ° from each other, the seal being ensured by a cylindrical seal.
• the upper part of the device is completed more precisely by an exchange column 6.
• This column open at its top, has a height of approximately 2 m, and has a cold air inlet, marked 7.
• the gas which arrives escapes from the top of the column and circulates in this column against the falling drops of water.
• the exchange column 6 is placed on a receptacle 8, extending the latter at its lower end.
• This receptacle 8 has a ramp 12 for bringing the coolant inside the device. Under this ramp 12, the bottom of the receptacle is formed by a cone 10 at the bottom of which is a bath 11 of coolant and where the already formed ice balls collect.
• the receptacle also has, at the bottom of this cone 10, an orifice 14 provided for discharging the ice balls.
• the injector 2 disperses at the top of the exchange column 6 a spectrum of water droplets, falling by gravity into the exchange column, and represented by arrows. In direct contact with cold gas flowing against the current, these droplets partially and surface freeze. They fall by gravity in the exchange column 6, and thus fall into the bath 11 of coolant located in the cone 10 of the receptacle 8, where they solidify completely and descend by gravity to the bottom of the cone 10.
• the invention provides for evacuating the ice balls by means of an extraction screw 16, a first end 17 of which is placed below the orifice 14 of the receptacle 8.
• the extraction screw is inclined, so as to raise the ice balls outside the manufacturing device, to a level at least higher than that of the coolant bath inside the receptacle 8.
• a recovery duct 22 is provided in the wall of the receptacle, connecting the upper part of the cavity in which the extraction screw 16 is located with the interior of the receptacle 8, for recovering the coolant by returning it to the bath 11 inside the receptacle 8.
• the recovery conduit 22 is provided of a grid
• the grid 23 separates the coolant to be recycled from the beads ice being extracted.
• the extraction screw is rotated by means of a motor 18, preferably placed at the upper end 19 of this extraction screw 16.
• the projection device according to the invention is completed with a cold gas inlet 20 at the second end 19 of the extraction screw 16, to push the ice balls into a first conduit f l ex i b l e
• the actual projection of the ice balls is carried out by means of a projection nozzle 26, placed at the end of the first flexible conduit 24.
• This projection nozzle 26 has a cold gas inlet 28, supplied by a second flexible conduit 44, in order to carry out the projection of the ice balls.
• the device according to the invention can be fitted with a storage tank 32 for the refrigerating body, namely nitrogen.
• the latter leaves this tank 32 in the liquid state, and is brought into an evaporator 34, to supply the cold gas under pressure necessary to supply the inlet 7 inside the exchange column 6 and the arrivals of cold gas 20, at the upper end 19 of the extraction screw 16, and at the point 28 of the nozzle 26.
• the cooling of the gas from the evaporator 34 is produced using a cooler 36 placed at the outlet of this evaporator 34. This cooler is supplied by the same body in the liquid state and coming directly from the storage tank 32. This the latter also directly feeds the ramp 12 inside the receptacle 8. It is possible to use a single distributor 30 of the cold gas to supply the inlet 20 to the upper end 19 of the extraction screw 16 and the inlet 28 of the projection nozzle 26.
• a condition for the proper functioning of the device according to the invention is that the gas flow rate, in this case nitrogen at the temperature of 133 ° K, must be greater than or equal to three hundred and fifty times the water flow rate ( V nitrogen at 133 ° K ⁇ 350 V water ).
• the water inlet pipe 1 can be produced by means of a copper tube fitted with a valve of the type
• the flow meter 3 can be of the KHRONE float type measuring a flow range of 25 to 250 liters of water per hour.
• the injector 2 can be produced by a PVC (polyvinyl chloride) tank pierced with eighty holes 4 of 0.5 mm in diameter to obtain an average diameter spectrum of 1.5 mm. In general the diameter of the holes 4 will be chosen between 0.1 mm and 1 mm.
• the exchange column is a double-walled stainless steel cylinder 40, 41, with a height of 2 m, the inside diameter of which is around 400 mm and the outside diameter of 500 mm. The space between these two walls 40 and 41 is filled by injection of an insulating material 45, such as polyurethane foam. This therefore represents an insulation thickness greater than 50 mm.
• the receptacle 8 supporting this exchange column 6 is made of the same material. It also has a double wall 42, 43, maintaining the insulation, which is of the same type as that of column 6, and the thickness of which is also greater than 50 mm.
• the ramp 12 for supplying the coolant is preferably metallic and circular. After a fall of around 2.50 m, the droplets of water are not completely solidified. They fall into the bath 11 of cooling liquid during solidification. A large number of them then split into two half-spheres during the end of their solidification. This phenomenon is explained by the volume expansion resulting from the change of physical state of the water in ice.
• the ice balls thus obtained are entrained by the extraction screw 16 which is preferably an Archimedes screw of pure form.
• the balls are sucked in by the venturi effect produced by the flow of nitrogen cooled to 130 ° K, under a pressure of 10 6 Pa, arriving at 28.
• the nitrogen gas is cooled upstream in a cooler 34, which makes it possible, from liquid nitrogen at 77 ° K, to obtain nitrogen gas at 133 ° K.
• the production of the ice balls is carried out below the temperature of 193 ° K, this to avoid the phenomenon of coalescence of the ice balls.
• the height of approximately 2.50 m of the exchange column 6 allows the water droplets to solidify a sufficient crust, to have good mechanical strength, and a temperature of surface below this coalescing temperature.
• the use of an Archimedes 16 screw of pure shape, having no dead volume, allows a continuous flow of the bed of ice beads.
• the motor 18 for driving the screw 16 can be a CLER geared motor, with variable speed of rotation, so as to be able to vary the rate of extraction of the ice balls and reversible to eliminate accidental dams of the screw.
• the ice balls are sucked in and pushed by the venturi effect generated by the large flow of cold gas arriving at 28 in the nozzle 26, and pushed by the gas arriving at 20.
• the flexible tube 24 bringing the ice balls into the nozzle 26 may be a flexible Cryoflex 200 tube, distributed by Tift establishments, and thermally insulated. These are flexible hoses of the same type which can be used to convey cold gases to the inlet 20, to the end of the extraction ball 16 and to the inlet 28 of the projection nozzle 26.
• the nozzle itself even may be of the CAR 303 type, distributed by CARBORID establishments.
• the ice balls obtained by means of the invention can have a diameter of between 0.5 and 2 mm.
• the extraction screw 16 is preferably inclined at an angle of 45 °, and thus tangent to the wall of the cone 10. The thrust of the cold gas, then the depression produced in the spray nozzle 26 entrain the ice balls in the flow of cold gas from the first flexible conduit 24 and project them at a pressure of 7 ⁇ 10 5 Pa.
• One of the main advantages of the method and of the device according to the invention is that the latter leads to the design of an integral device.
• the device makes it possible to manufacture on the spot balls of ice and to project them against the objects to be treated.
• the beads may contain a chemical mixed with water before introduction into the device and before freezing.
• This chemical can be chosen so as to complete the mechanical attack by a chemical passivation treatment for example, or by a disinfection treatment in the case of bacteriological cleaning.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Carbon And Carbon Compounds (AREA)
• Cleaning In General (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)
• Nozzles (AREA)

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• 1988
  • 1988-04-28 FR FR8805692A patent/FR2630668B1/fr not_active Expired - Lifetime
• 1989
  • 1989-04-26 CA CA000597895A patent/CA1331698C/fr not_active Expired - Fee Related
  • 1989-04-27 KR KR1019890702439A patent/KR900700833A/ko not_active Withdrawn
  • 1989-04-27 DE DE68914657T patent/DE68914657T2/de not_active Expired - Fee Related
  • 1989-04-27 EP EP89905697A patent/EP0412111B1/de not_active Expired - Lifetime
  • 1989-04-27 WO PCT/FR1989/000204 patent/WO1989010522A1/fr not_active Ceased
  • 1989-04-28 ES ES8901496A patent/ES2011566A6/es not_active Expired - Lifetime

Non-Patent Citations (1)

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